/**
 * Copyright (C) 2007, 2008 Carnegie Mellon University and others.
 *
 * This file is part of Plural.
 *
 * Plural is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Plural is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Plural; if not, see <http://www.gnu.org/licenses>.
 *
 * Linking Plural statically or dynamically with other modules is
 * making a combined work based on Plural. Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 *
 * In addition, as a special exception, the copyright holders of Plural
 * give you permission to combine Plural with free software programs or
 * libraries that are released under the GNU LGPL and with code
 * included in the standard release of Eclipse under the Eclipse Public
 * License (or modified versions of such code, with unchanged license).
 * You may copy and distribute such a system following the terms of the
 * GNU GPL for Plural and the licenses of the other code concerned.
 *
 * Note that people who make modified versions of Plural are not
 * obligated to grant this special exception for their modified
 * versions; it is their choice whether to do so. The GNU General
 * Public License gives permission to release a modified version
 * without this exception; this exception also makes it possible to
 * release a modified version which carries forward this exception.
 */
package edu.cmu.cs.plural.perm.parser;

/**
 * Objects of this class represent Permission implications which can be specified
 * in state invariants. Permission invariants look like this:
 * 
 * <pre> 
 * inv="isNormal == true => unique(head)"
 * inv="isNormal != false implies full(tail)" 
 * </pre>
 * 
 * Implications always have an antecedent and a consequent. For now even though
 * both fields are of type AccessPred, they can really only be the Java binary
 * expressions that are supported.
 * 
 * @author Nels Beckman
 * @date Apr 22, 2008
 *
 */
public class PermissionImplication implements AccessPred {

	private final BinaryExpr antecedent;
	private final AccessPred consequent;
	
	public PermissionImplication(BinaryExpr ant, AccessPred cons) {
		this.antecedent = ant;
		this.consequent = cons;
	}

	@Override
	public <T> T accept(AccessPredVisitor<T> visitor) {
		return visitor.visit(this);
	}
	
	/**
	 * @return the antecedent access predicate.
	 */
	public BinaryExpr ant() {
		return antecedent;
	}
	
	/**
	 * @return the consequent access predicate.
	 */
	public AccessPred cons() {
		return consequent;
	}
}
